//========================================================================
//Copyright 2007-2009 David Yu dyuproject@gmail.com
//------------------------------------------------------------------------
//Licensed under the Apache License, Version 2.0 (the "License");
//you may not use this file except in compliance with the License.
//You may obtain a copy of the License at 
//http://www.apache.org/licenses/LICENSE-2.0
//Unless required by applicable law or agreed to in writing, software
//distributed under the License is distributed on an "AS IS" BASIS,
//WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
//See the License for the specific language governing permissions and
//limitations under the License.
//========================================================================

// Protocol Buffers - Google's data interchange format
// Copyright 2008 Google Inc.  All rights reserved.
// http://code.google.com/p/protobuf/
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
//     * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
//     * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
//     * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

package io.protostuff;

/**
 * This class is used internally by the Protocol Buffer library and generated message implementations. It is public only
 * because those generated messages do not reside in the {@code protobuf} package. Others should not use this class
 * directly.
 * <p>
 * This class contains constants and helper functions useful for dealing with the Protocol Buffer wire format.
 * 
 * @author kenton@google.com Kenton Varda
 * @author David Yu
 */
public final class WireFormat
{
    // Do not allow instantiation.
    private WireFormat()
    {
    }

    public static final int WIRETYPE_VARINT = 0;
    public static final int WIRETYPE_FIXED64 = 1;
    public static final int WIRETYPE_LENGTH_DELIMITED = 2;
    public static final int WIRETYPE_START_GROUP = 3;
    public static final int WIRETYPE_END_GROUP = 4;
    public static final int WIRETYPE_FIXED32 = 5;
    public static final int WIRETYPE_REFERENCE = 6;
    public static final int WIRETYPE_TAIL_DELIMITER = 7;

    static final int TAG_TYPE_BITS = 3;
    static final int TAG_TYPE_MASK = (1 << TAG_TYPE_BITS) - 1;

    /**
     * Given a tag value, determines the wire type (the lower 3 bits).
     */
    public static int getTagWireType(final int tag)
    {
        return tag & TAG_TYPE_MASK;
    }

    /**
     * Given a tag value, determines the field number (the upper 29 bits).
     */
    public static int getTagFieldNumber(final int tag)
    {
        return tag >>> TAG_TYPE_BITS;
    }

    /**
     * Makes a tag value given a field number and wire type.
     */
    public static int makeTag(final int fieldNumber, final int wireType)
    {
        return (fieldNumber << TAG_TYPE_BITS) | wireType;
    }

    /**
     * This is here to support runtime schemas.
     */
    public enum JavaType
    {
        INT(0),
        LONG(0L),
        FLOAT(0F),
        DOUBLE(0D),
        BOOLEAN(false),
        STRING(""),
        BYTE_STRING(ByteString.EMPTY),
        ENUM(null),
        MESSAGE(null);

        JavaType(final Object defaultDefault)
        {
            this.defaultDefault = defaultDefault;
        }

        /**
         * The default default value for fields of this type, if it's a primitive type.
         */
        Object getDefaultDefault()
        {
            return defaultDefault;
        }

        private final Object defaultDefault;
    }

    /**
     * This is here to support runtime schemas.
     */
    public enum FieldType
    {
        DOUBLE(JavaType.DOUBLE, WIRETYPE_FIXED64),
        FLOAT(JavaType.FLOAT, WIRETYPE_FIXED32),
        INT64(JavaType.LONG, WIRETYPE_VARINT),
        UINT64(JavaType.LONG, WIRETYPE_VARINT),
        INT32(JavaType.INT, WIRETYPE_VARINT),
        FIXED64(JavaType.LONG, WIRETYPE_FIXED64),
        FIXED32(JavaType.INT, WIRETYPE_FIXED32),
        BOOL(JavaType.BOOLEAN, WIRETYPE_VARINT),
        STRING(JavaType.STRING, WIRETYPE_LENGTH_DELIMITED)
        {
            @Override
            public boolean isPackable()
            {
                return false;
            }
        },
        GROUP(JavaType.MESSAGE, WIRETYPE_START_GROUP)
        {
            @Override
            public boolean isPackable()
            {
                return false;
            }
        },
        MESSAGE(JavaType.MESSAGE, WIRETYPE_LENGTH_DELIMITED)
        {
            @Override
            public boolean isPackable()
            {
                return false;
            }
        },
        BYTES(JavaType.BYTE_STRING, WIRETYPE_LENGTH_DELIMITED)
        {
            @Override
            public boolean isPackable()
            {
                return false;
            }
        },
        UINT32(JavaType.INT, WIRETYPE_VARINT),
        ENUM(JavaType.ENUM, WIRETYPE_VARINT),
        SFIXED32(JavaType.INT, WIRETYPE_FIXED32),
        SFIXED64(JavaType.LONG, WIRETYPE_FIXED64),
        SINT32(JavaType.INT, WIRETYPE_VARINT),
        SINT64(JavaType.LONG, WIRETYPE_VARINT);

        FieldType(final JavaType javaType, final int wireType)
        {
            this.javaType = javaType;
            this.wireType = wireType;
        }

        public final JavaType javaType;
        public final int wireType;

        public JavaType getJavaType()
        {
            return javaType;
        }

        public int getWireType()
        {
            return wireType;
        }

        public boolean isPackable()
        {
            return true;
        }
    }

    // Field numbers for feilds in MessageSet wire format.
    static final int MESSAGE_SET_ITEM = 1;
    static final int MESSAGE_SET_TYPE_ID = 2;
    static final int MESSAGE_SET_MESSAGE = 3;

    // Tag numbers.
    static final int MESSAGE_SET_ITEM_TAG =
            makeTag(MESSAGE_SET_ITEM, WIRETYPE_START_GROUP);
    static final int MESSAGE_SET_ITEM_END_TAG =
            makeTag(MESSAGE_SET_ITEM, WIRETYPE_END_GROUP);
    static final int MESSAGE_SET_TYPE_ID_TAG =
            makeTag(MESSAGE_SET_TYPE_ID, WIRETYPE_VARINT);
    static final int MESSAGE_SET_MESSAGE_TAG =
            makeTag(MESSAGE_SET_MESSAGE, WIRETYPE_LENGTH_DELIMITED);
}
